WASHINGTON — Orbital Sciences Corp. is planning to end its first cargo delivery mission to the international space station a little early, with the company’s now-trash-filled Cygnus spacecraft set for destructive re-entry over the Pacific Ocean Oct. 23, a spokesman said.

“It used to be Oct. 24, but in looking at the orbital mechanics of release, the team updated their burn schedule and Oct. 24 became Oct. 23,” Orbital spokesman Barron Beneski said in a phone interview Oct. 16.

Space station crew members will close Cygnus’ hatch Oct. 21. Then, around 5 a.m. Eastern time the next day, the craft will separate from the station’s Harmony node and maneuver away from the outpost to perform its deorbit burn.

Cygnus launched Sept. 18 from the state-run Mid-Atlantic Regional Spaceport at NASA’s Wallops Flight Facility on Wallops Island, Va. The expendable cargo ship arrived at the station Sept. 29, a few days later than expected after a communications glitch and the arrival of new crew members aboard a Russian-launched Soyuz spacecraft forced Cygnus into a holding pattern.

The same day the first Cygnus plunges through the atmosphere in flames, the service module for the next Cygnus could be on its way from Orbital’s Dulles, Va., headquarters to the company’s horizontal integration facility at Wallops, Beneski said. There, it will be mated with its Italian-built pressurized cargo module in preparation for a mission that could launch aboard Orbital’s Antares rocket as soon as December.

The capsule can be loaded with cargo only once NASA is sure that the initial Cygnus mission was successful, and gives Orbital formal approval to make the December cargo run — the first of eight the company owes NASA under a $1.9 billion Commercial Resupply Services contract signed in 2008. Orbital has already received some advance payments on this contract but cannot claim additional fees until after it completes each of the missions it is slated to carry out through 2016.

Meanwhile, whatever effect the government shutdown will have on other aspects of Orbital’s business — Beneski said financial analysts are sure to ask about that on a quarterly conference call scheduled for Oct. 17 — the company’s space station logistics work appears to have been disturbed only minimally, if at all.

Neither Orbital nor the Virginia Commercial Space Flight Authority got locked out of the Mid-Atlantic Regional Spaceport as a result of the shutdown, meaning that preparations for the tentative December launch continued while more than 95 percent of NASA’s roughly 18,000 civil servants were on furlough.

“The first-stage core for this December Antares is at Wallops, the upper-stage rocket motor is there, the fairing is there, the two AJ-26 engines for the core are there,” Beneski said. “We have all necessary major components of the Antares rocket onsite. The expectation is on our part that if we’re ready to go in December and NASA is ready to receive us, we will go in December.”